The present invention relates to an ink jet system printer and, more particularly, to a charging electrode in an ink jet system printer.
Generally, there are two types of ink jet system printers. One is the charge amplitude controlling type, and the other is the deflection field controlling type.
In an ink jet system printer of the charge amplitude controlling type, a stream of ink droplets having a given frequency is emitted from a nozzle toward a record receiving paper and each ink droplet is charged to a desired amplitude in accordance with a video signal through the use of a charging electrode. Each ink droplet is deflected as it passes through a fixed high voltage field established by a pair of deflection plates in accordance with the charge amplitude carried thereon and deposited at a desired position on the record receiving paper.
In an ink jet system printer of the deflection field controlling type, uniformly charged ink droplets are propelled from a nozzle toward a record receiving paper through the use of an acceleration electrode. The deflection field is varied in accordance with print information to deflect the ink droplets by desired magnitudes.
In the above-mentioned types of ink jet system printers, ink mist is inevitably created when the ink droplets impinge on the record receiving paper or when the ink droplets are formed from a solid stream of ink ejected from the nozzle. There is a possibility that the ink mist will become attached to the inner surface of the charging electrode or the acceleration electrode confronting the stream of the ink droplets. When the ink mist attached to the inner surface of the charging electrode or the acceleration electrode accumulates to become an ink drop, the ink drop damages the accurate charge operation. Moreover, when the thus created ink drop becomes large, there is a possibility that the ink droplets emitted from the nozzle will come into collision with the ink drop attached to the inner surface of the charging electrode or the acceleration electrode.